The present invention relates to a paper feeder mounted in an image-forming machine such as copier, facsimile or printer to feed a paper toward an image-forming unit.
The conventional image-forming machine is equipped with a paper feeder which takes out, piece by piece, papers stacked on a paper-feed tray starting from the uppermost one, and feeds it toward the image-forming unit. The paper feeder that is widely and practically used is of the type in which a feed roller is brought into contact with the paper at the uppermost position stacked on the paper-feed tray to feed the paper by frictional force. In the paper feeder of the type in which the feed roller is brought into contact with the paper to feed it, however, slipping occurs between the feed roller and the paper when the feed roller is worn out, thereby causing the paper to be contaminated. Furthermore, when the feed roller is worn out to a great extent, the paper is not fed smoothly. Therefore, a problem resides in the durability of the feed roller.
The paper feeder is further equipped with a paper separation means for separating the paper at the uppermost position from the second and subsequent papers stacked on the paper-feed tray. The paper separation means is generally of a pawl separation type, friction pad type or gate type. However, none of them is capable of reliably separating a paper from the subsequent papers, and there occurs often feeding of plural pieces of papers at one time in an overlapped manner or occurrence of clogging of paper.
In order to solve the problems of the paper feeder equipped with the above-mentioned feeder roller and the paper separation mechanism, Japanese Unexamined Patent Publication (Kokai) No. 107347/1994 (JP-A 6-107347) discloses a paper feeder of the air suction type. The paper feeder of the air suction type comprises a paper-stacking means for stacking the papers; a suction/feed means having a drive roller and a driven roller arranged above the paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between the drive roller and the driven roller and having a suction port in the bottom wall thereof, and a conveyer belt arranged being wrapped round the drive roller, driven roller and suction duct and having plural holes formed therein; and an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed, which includes an air duct equipped with plural floatation nozzles to jet out the air against an upper portion at the front end of the papers stacked on the paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of the suction/feed means. The air jetted out from the floatation nozzles is blown to the upper portion of the papers stacked on the paper-stacking means to float several pieces of upper papers. The paper at the uppermost position thus floated is sucked and conveyed by a feed belt of the suction/feed means. On the other hand, the thus floated papers other than the uppermost paper are separated from the uppermost paper by the air that is jetted out from the separation nozzles and enters between the uppermost paper and the second paper. In order to reliably separate one paper from the other, the air must be reliably introduced between the uppermost paper and the second and subsequent papers. For this purpose, according to the paper feeder disclosed in Japanese Unexamined Patent Publication (Kokai) No. 107347/1994, a protrusion is provided on the lower surface of the bottom wall of the suction duct to come into contact with the conveyer belt thereby to give a curve to the conveyer belt, so that the paper adsorbed by the conveyer belt is caused to have undulation. Consequently, the air can easily enters between the uppermost paper and the second paper.
The above paper-stacking means comprises a frame that is mounted to freely move between an acting position and a non-acting position drawn out from the acting position, and a paper-stacking plate mounted on the frame to freely move up and down. The frame is drawn out to the non-acting position, and plural papers are stacked on the paper-stacking plate as required. Then, the frame is returned back to the acting position so that the plural papers stacked on the paper-stacking plate are positioned as required with respect to the air-blowing means and the suction/feed means.
The paper feeder further includes a means for holding down the rear end of the papers and for detecting the height of the papers. The means for holding down the rear end of the papers and for detecting the height of the papers includes a support member, a pushing member mounted on the support member so as to move over a predetermined range in a direction toward the paper-stacking plate and in a direction to separate away therefrom, and a detector for detecting the position of the pushing member. The pushing member is pushed at its lower end to the uppermost paper of the plural papers on the paper-stacking plate to prevent the papers on the paper-stacking plate from moving backward by the air sent from the air-blowing means. Further, the position or height of the pushing member is detected by the detector to detect the height of the uppermost paper on the paper-stacking plate, that is pushed by the lower end of the pushing member. As a considerable number of pieces of papers on the paper-stacking plate are consumed and the height of the uppermost paper on the paper-stacking plate becomes lower than a predetermined threshold value, the paper-stacking plate is elevated by a required amount.
In the conventional paper feeder of the air suction type, plural floatation nozzles and separation nozzles provided in the air duct constituting the air-blowing means are arranged in a range corresponding to a maximum paper size. When the papers of small sizes are used, therefore, the air jetted from the nozzles also act onto both sides of the papers placed on the paper-stacking means. As a result, there arises a problem that there occurs a so-called overlapped paper feeding in which the papers are excessively floated and plural papers are fed at one time.
In the paper feeder disclosed in the above Japanese Unexamined Patent Publication (Kokai) No. 107347/1994, the protrusions are provided on the side of the suction ports. Therefore, the paper adsorbed by the conveyer belt is excessively undulated due to the mutual action between the protrusions and the suction. Consequently, the undulation remains on the paper even after being conveyed and it is liable to cause a paper clogging (jamming) in the subsequent conveyance.
Further, even when the uppermost paper and the second and subsequent papers are relatively smoothly separated, there often occurs the so-called overlapped paper feeding in which plural pieces of papers are fed at one time when there is some distance between the feed belt and the separation nozzles.
Desirably, the plural floatation nozzles and separation nozzles provided in the air duct constituting the air-blowing means are selected for their number and arrangement according to the size of the papers and the quality (weight) of the papers. In the conventional paper feeder, however, the floatation nozzles and the separation nozzles are formed in one member that constitutes the air duct. To cope with the papers of various sizes and various qualities, therefore, there must be provided air ducts of several kinds having floatation nozzles and separation nozzles in various numbers and in various arrangements, resulting in an increase in the cost.
In the above-mentioned paper feeder of the air suction type, the papers stacked on the paper-stacking means float in different conditions based on the velocity of the air blown from the plural floatation nozzles provided in the air duct constituting the air-blowing means. That is, when the air velocity is set to be adapted to thick and heavy papers, the thin papers are excessively floated giving rise to the occurrence of the so-called overlapped paper feeding. When the air velocity is set to be adapted to the thin papers, on the other hand, the thick papers are not floated as desired, and no feeding of paper will occur.
In the above-mentioned conventional paper feeder, the air is simultaneously jetted out from the plural floatation nozzles and separation nozzles provided in the air duct constituting the air-blowing means. To supply the air simultaneously jetted out from the plural floatation nozzles and separation nozzles, however, a fan of a large capacity is required, resulting in an increase in the cost and in hindrance for realizing the apparatus in a compact size as a whole.
In the above-mentioned conventional paper feeder of the air suction type, the frame must be drawn out from the acting position to the non-acting position when the papers stacked on the paper-stacking plate are to be replaced by the papers of a different size. At this time, the pushing member pushing the uppermost paper stacked on the paper-stacking plate must be moved upward to be separated away from the uppermost paper prior to drawing out the frame. Also when the frame is to be returned from the non-acting position back to the acting position after the plural pieces papers have been stacked on the paper-stacking plate, it becomes necessary to move the pushing member upward so that the pushing member will not act on the uppermost paper on the paper-stacking plate. Otherwise, the uppermost paper is hindered from moving since it is pushed by the pushing member at the time when the paper-stacking plate is moved following the drawing out of the frame, and it drops from the paper-stacking plate and, in some cases, the subsequent several pieces of papers, too, drop from the paper-stacking plate. However, the conventional paper feeder is not equipped with any suitable means for moving the pushing member upward so as to be separated away from the uppermost paper on the paper-stacking plate and hence, cumbersome manual operation is needed for moving the pushing member upward.
Further, the conventional paper feeder often causes the so-called overlapped paper feeding in which the uppermost piece of paper and the second piece or several pieces of papers on the paper-stacking plate are fed simultaneously, or often causes a defective paper feeding in which the uppermost paper is not fed from the paper-stacking plate despite the air-blowing means and the suction/feed means are actuated.
It is the first object of the present invention to provide a paper feeder equipped with an air-blowing means which is capable of floating the papers properly correspondingly to their sizes and preventing the overlapped paper feeding beforehand.
It is the second object of the present invention to provide a paper feeder which is capable of enhancing the paper separation performance by undulating the paper adsorbed by conveyer belts and of eliminating the undulation of the paper after it is conveyed.
The present invention further provides a paper feeder capable of preventing the so-called overlapped paper feeding in which plural pieces of papers are fed at one time.
It is the third object of the present invention to provide a paper feeder equipped with an air-blowing means having an air duct capable of easily changing the number and arrangement of the floatation nozzles and separation nozzles depending upon the size and the quality of the papers.
It is the fourth object of the present invention to provide a paper feeder equipped with an air-blowing means capable of suitably adjusting the velocity of the air jetted out from plural floatation nozzles provided in the air duct.
It is the fifth object of the present invention to provide a paper feeder which can reduce the capacity of a fan constituting the air-blowing means.
It is the sixth object of the present invention to provide a novel and improved paper feeder which enables a pushing member to be automatically located at an elevated position at the time when a frame of the paper-stacking means is moved from an acting position to a non-acting position or from the non-acting position to the acting position.
It is the seventh object of the present invention to provide a novel and improved paper feeder which scarcely permits occurrence of the overlapped paper feeding in which plural pieces of papers are fed at one time from the paper-stacking plate or occurrence of defective paper feeding in which no paper is fed from the paper-stacking plate.
In order to accomplish the above-mentioned first object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means having a paper-stacking plate on which the papers are to be stacked, and a width-limiting member for limiting the position in the width direction of the papers stacked on said paper-stacking plate;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed and including an air duct that extends in a direction at right angles with the direction in which the paper is conveyed and has plural nozzles for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means, and a fan connected to an end of said air duct; wherein
said width-limiting member is provided with a closure member for closing the nozzles located on the outer sides of said width-limiting member, of said plural nozzles.
According to the present invention, there is further provided a paper feeder comprising a paper size detection means for detecting the position of said width-limiting member, and a control means for controlling the air amount of said fan based on a detection signal sent from said paper size detection means.
In order to accomplish the above-mentioned second object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports in the bottom wall thereof, and conveyer belts arranged wrapped round said drive roller, driven roller and suction port in said suction duct and having plural holes; and
an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed and including an air duct extending in a direction at right angles with the direction in which the paper is conveyed to jet out the air against an upper portion at the front end of the papers stacked on said paper-stacking means, and a fan connected to an end of said air duct; wherein
said suction duct has ribs formed on the lower surface of the bottom wall on the upstream sides of said suction ports in the direction in which the paper is conveyed to come into contact with the conveyer belts.
The suction ports are formed in a plural number in the direction at right angles with the direction in which the paper is conveyed, and the ribs are formed on the upstream sides of the plural suction ports in the direction in which the paper is conveyed. It is desired that the ribs protrude by an amount of 1.5 to 3.5 mm from the lower surface of the bottom wall of the suction duct.
In order to accomplish the above-mentioned second object according to the present invention, there is further provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports in the bottom wall thereof, and conveyer belts arranged wrapped round said drive roller, said driven roller and said suction ports in said suction duct and having plural holes; and
an air-blowing means including an air duct with plural floatation nozzles for jetting the air against an upper portion at the front end of the papers stacked on said paper-stacking means and plural separation nozzles for jetting the air toward the lower surface of said suction/feed means, and a fan connected to an end of said air duct; wherein
a paper-limiting member made of a flexible elastic material is provided at a positioned near the lower surfaces of said conveyer belts on the downstream side of the papers stacked on said paper-stacking means in the direction in which the paper is conveyed.
It is desired that a gap between the upper end of the paper-limiting member and the lower surfaces of said conveyer belts is set to be 0.5 to 3 mm.
In order to accomplish the above-mentioned second object according to the present invention, there is further provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports in the bottom wall thereof, and plural conveyer belts arranged wrapped round said drive roller, driven roller and suction ports in said suction duct and having plural holes; and
an air-blowing means including an air duct with plural floatation nozzles for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means, and a fan connected to an end of said air duct; wherein
ribs are formed protruding downward on the lower surface of the bottom wall of said suction duct to come into contact with said conveyer belts; and
a paper-limiting member made of a flexible elastic material is provided being arranged between said conveyer belt and said conveyer belt on the downstream side of the papers stacked on said paper-stacking means in the direction in which the paper is conveyed.
It is desired that the upper end of said paper-limiting member is not lower than the lowermost point but is not higher than the uppermost point of the paper that is undulated by being adsorbed by said conveyer belts.
In order to accomplish the above-mentioned third object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed and including an air duct having plural floatation nozzles for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means; wherein
said air duct of said air-blowing means is constituted by a base board extending in a direction at right angles with the direction in which the paper is conveyed and plural blocks mounted on said base board to form an air passage together with said base board; and
said plural blocks include the first blocks having said floatation nozzles and the second blocks having said separation nozzles.
According to the present invention, further, there is provided a paper feeder wherein said plural blocks include the first blocks having said floatation nozzles and the third blocks having said floatation nozzles as well as said separation nozzles.
According to the present invention, further, there is provided a paper feeder wherein said plural blocks include the first blocks having said floatation nozzles, the second blocks having said separation nozzles, and the third blocks having said floatation nozzles as well as said separation nozzles.
It is desired that said plural blocks include space blocks having neither said floatation nozzle nor said separation nozzle, and both sides of said air duct are constituted by said space blocks.
In order to accomplish the above-mentioned fourth object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed and including an air duct extending in a direction at right angles with the direction in which the paper is conveyed to jet the air against an upper portion at the front end of the papers stacked on said paper-stacking means, and a fan connected to an end of said air duct; wherein
said air duct has plural floatation nozzles for jetting the air against an upper portion at the front end of the papers stacked on said paper-stacking means, an air-escape hole, and an escape hole-shutter mechanism for changing the opening area of said air-escape hole.
The floatation nozzles are formed in a side wall that constitutes the air duct, and the air-escape hole is formed in an end wall that constitutes the air duct. It is desired that the air duct has plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means.
In order to accomplish the above-mentioned fourth object according to the present invention, there is further provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means disposed on the front side of the paper-stacking means in the direction in which the papers are conveyed and including an air duct extending in a direction at right angles with the direction in which the paper is conveyed to jet out the air against an upper portion at the front end of the papers stacked on said paper-stacking means, and a fan connected to an end of said air duct; wherein
said air duct has plural floatation nozzles formed in the side wall for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means, an air-escape hole, and a nozzle shutter mechanism for changing the opening area of said plural nozzle.
It is desired that said air duct has plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means, and said nozzle shutter mechanism changes the opening areas of the separation nozzles.
In order to accomplish the above-mentioned fifth object, the present inventors have found through experiment that the floatation of the papers by the air jetted from the floatation nozzles and the separation of the uppermost paper and the second and subsequent papers by the air jetted from the separation nozzles are not always necessary to execute simultaneously, i.e., the separation of the papers may be executed at a moment when the uppermost paper is sucked by the conveyer belts of the suction/feed means after the papers are floated, and that the capacity of the fan can be made small by selectively changing over the timing for jetting the air through the floatation nozzles and the timing for jetting the air through the separation nozzles.
That is, in order to accomplish the above-mentioned fifth object according to the present invention, there is provided a paper feeder that solves the above technical problem, comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means including an air duct with plural floatation nozzles for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means; wherein
said air-blowing means is equipped with an air blow change-over mechanism for suitably changing over the air jetted through said floatation nozzles or said separation nozzles.
The air blow change-over mechanism includes a shutter plate for selectively closing said floatation nozzles or said separation nozzles, and a drive mechanism that moves said shutter plate to the first position to close said separation nozzles and open said floatation nozzles, and to the second position to close said floatation nozzles and open said separation nozzles. Said shutter plate is mounted on a rotary shaft disposed in said air duct, and said drive mechanism pivots the rotary shaft in one direction or in the other direction so that the shutter plate is brought to said first position or said second position. Further, the shutter plate is arranged to slide along the outer peripheral surface of said air duct, and said drive mechanism moves the shutter plate in one direction or in the other direction so that the shutter plate is brought to said first position or said second position.
In order to accomplish the above-mentioned fifth object according to the present invention, there is further provided a paper feeder comprising:
a paper-stacking means on which the papers are to be stacked;
a suction/feed means having a drive roller and a driven roller arranged above said paper-stacking means in parallel with each other and spaced out in a direction in which the paper is conveyed, a suction duct arranged between said drive roller and said driven roller and having suction ports, and conveyer belts arranged wrapped round said drive roller, driven roller and suction duct and having plural holes; and
an air-blowing means including an air duct with plural floatation nozzles for jetting out the air against an upper portion at the front end of the papers stacked on said paper-stacking means and plural separation nozzles for jetting out the air toward the lower surface of said suction/feed means; wherein
said air-blowing means includes a shutter plate for selectively closing said floatation nozzles or said separation nozzles, an air blow change-over mechanism that moves said shutter plate to the first position to close said separation nozzles and open said floatation nozzles and moves said shutter plate to the second position to close said floatation nozzles and open said separation nozzles, a paper adsorption detection means for detecting whether the paper is adsorbed by the conveyer belts of said suction/feed means, and a control means for controlling the operation of said air blow change-over mechanism based on a detection signal from said paper adsorption detection means; and
based on the detection signal from said paper adsorption detection means, said control means so controls said air blow change-over means that said shutter plate is brought to said first position when no paper is adsorbed by said conveyer belts and that said shutter plate is brought to said second position when a paper is adsorbed by said conveyer belts.
In order to accomplish the above-mentioned sixth object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means including a paper-stacking plate on which the papers are to be stacked and which moves up and down;
an air-blowing means for blowing the air onto an upper portion at the front end of plural papers stacked on said paper-stacking plate;
a suction/feed means for sucking and feeding the uppermost paper of the plural papers stacked on said paper-stacking plate; and
a means for holding down the rear end of the papers and for detecting the height of the papers, which includes a support member, a pushing member mounted on said support member to move in a direction toward said paper-stacking plate and in a direction to separate away therefrom within a predetermined range, and a detector for detecting the position of said pushing member; wherein
said paper-stacking means includes a frame that freely moves between an acting position and a non-acting position drawn out from said acting position, said paper-stacking plate being mounted on said frame;
said support member of said means for holding down the rear end of the papers and for detecting the height of the papers is mounted to move between a pushing/detecting position and a separated position;
when said frame of said paper-stacking means moves to said acting position, said support member of said paper holding/detecting means is brought to said pushing/detecting position where said pushing member is pushed onto the uppermost paper of the papers stacked on said stacking plate; and
when said frame of said paper-stacking means moves from said acting position to said non-acting position, said support member of said means for holding down the rear end of the papers and for detecting the height of the papers moves to said separated position from said pushing/detecting position, and said pushing member separates upward away from the uppermost paper of the papers stacked on said paper-stacking plate.
In the preferred embodiment, the paper holding/detecting means includes a resilient urging member for resiliently urging said support member to the separated position. When the frame of the paper-stacking means is moved to the acting position, the frame comes in contact with the support member to move the support member to the pushing/detecting position against the resilient urging action of the resilient urging means. The frame of the paper-stacking means is drawn forward substantially horizontally from the acting position to move to the non-acting position. A contact piece is disposed on the frame to protrude backward from the back surface thereof. When the frame of the paper-stacking means moves to the acting position, the contact piece comes in contact with the support member. The support member of the means for holding down the rear end of papers and for detecting the height of the papers is allowed to turn between the pushing/detecting position and the separated position.
In order to accomplish the above-mentioned sixth object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means including a paper-stacking plate on which plural pieces of papers are to be stacked and which moves up and down;
an air-blowing means for blowing the air onto an upper portion at the front end of plural papers stacked on said paper-stacking plate;
a suction/feed means for sucking and feeding the uppermost paper of the plural papers stacked on said paper-stacking plate; and
a means for holding down the rear end of the papers and for detecting the height of the papers, which includes a support member, a pushing member mounted on said support member to move in a direction toward said paper-stacking plate and in a direction to separate away therefrom within a predetermined range, and a detector for detecting the position of said pushing member; wherein
said paper-stacking means includes a frame that moves between an acting position and a non-acting position drawn out from said acting position, said paper-stacking plate being mounted on said frame;
said means for holding down the rear end of the papers and for detecting the height of the papers includes a push-release means which is selectively actuated to move said pushing member in a direction to separate away from said paper-stacking plate;
when said frame of said paper-stacking means moves to said acting position, the release action of said push-release means extinguishes and said pushing member is pushed onto the uppermost paper of the papers stacked on said paper-stacking plate; and
when said frame of said paper-stacking means moves from said acting position to said non-acting position, said pushing member separates upward away from the uppermost paper of the papers stacked on said paper-stacking plate due to the release action of said push-release means.
It is desired that the push-release means is constituted by an electromagnetic solenoid.
In order to accomplish the above-mentioned seventh object according to the present invention, there is provided a paper feeder comprising:
a paper-stacking means including a paper-stacking plate on which plural pieces of papers are to be stacked and which moves up and down;
an air-blowing means for blowing the air onto an upper portion at the front end of plural papers stacked on said paper-stacking plate;
a suction/feed means for sucking and feeding the uppermost paper of the plural papers stacked on said paper-stacking plate; and
a means for holding down the rear end of the papers and for detecting the height of the papers, which includes a support member, a pushing member mounted on said support member to move in a direction toward said paper-stacking plate and in a direction to separate away therefrom within a predetermined range, and a detector for detecting the position of said pushing member; wherein
plural kinds of papers of different sizes are selectively placed on said paper-stacking plate of said paper-stacking means, and front edges are aligned to a predetermined position irrespective of the kinds of the papers that are stacked on said paper-stacking plate; and
said support member of said means for holding down the rear end of the papers and for detecting the height of the papers can be freely adjusted for its position on said paper-stacking plate in the direction in which the paper is conveyed.
In a preferred embodiment, said means for holding down the rear end of the papers and for detecting the height of the papers includes an electric motor for moving said support member on said paper-stacking plate in the direction in which the sheet-like paper is conveyed and in the direction opposite thereto. The electric motor is drivably coupled to said support member through an externally threaded shaft extending on the paper-stacking plate in the direction in which the sheet-like paper is conveyed and in the opposite direction, and through internally threaded blocks screwed onto said externally threaded shaft.
In order to accomplish the above-mentioned seventh object according to the present invention, there is further provided a paper feeder comprising:
a paper-stacking means including a paper-stacking plate on which plural pieces of papers are to be stacked and which moves up and down;
an air-blowing means for blowing the air onto an upper portion at the front end of plural papers stacked on said paper-stacking plate;
a suction/feed means for sucking and feeding the uppermost paper of the plural papers stacked on said paper-stacking plate; and
a means for holding down the rear end of the papers and for detecting the height of the papers, which includes a support member, a pushing member mounted on said support member to move in a direction toward said paper-stacking plate and in a direction to separate away therefrom within a predetermined range, and a detector for detecting the position of said pushing member; wherein
said pushing member of said means for holding down the rear end of the papers and for detecting the height of the papers is pushed onto the uppermost paper of the sheet-like papers on said paper-stacking plate with a pressure of 10 to 80 g, and/or the contact area between the lower end of said pushing member of said means for holding down the rear end of the papers and for detecting the height of the papers and the uppermost paper of the sheet-like papers on said paper-stacking plate is not larger than 100 mm2; and/or said pushing member of said means for holding down the rear end of the papers and for detecting the height of the papers is pushed onto the uppermost paper on said paper-stacking plate at a position within 50 mm from the rear edge of the paper as viewed in the direction in which the paper is delivered from said paper-stacking plate.
Preferably, the pushing member of said means for holding down the rear end of the papers and for detecting he height of the papers is pushed onto the uppermost paper of the papers on said paper-stacking plate with a pressure of from 20 to 60 g. It is desired that the means for holding down the rear end of the papers and for detecting the height of the papers includes a resilient pushing means for resiliently urging the pushing member toward the paper-stacking plate. Preferably, the pushing member of said means for holding down the rear end of the papers and for detecting the height of the papers has a lower end of nearly a semispherical shape. Preferably, the pushing member of said means for holding down the rear end of the papers and for detecting the height of the papers is pushed onto the uppermost paper on said paper-stacking plate at a position within 30 mm from the rear edge of the paper as viewed in the direction in which the paper is delivered from said paper-stacking plate.